Pipe surface treating method for fuel cell system

Abstract

A method of electro-polishing an inner surface and an outer surface of a multi-bending pipe by letting a current flow to a positive electrode and a negative electrode in an electrolyte is provided. A mesh net having a shape corresponding to an inner shape of the multi-bending pipe and formed of an insulating material and an internal electrode disposed within the mesh net are placed within the multi-bending pipe. An external electrode is placed outside the multi-bending pipe such that the inner surface and the outer surface of the multi-bending pipe are electro-polished by applying a negative electrode to the internal electrode and the external electrode and applying a positive electrode to the multi-bending pipe.

What is claimed is: 
     
         1 . A method of electro-polishing an inner surface and an outer surface of a multi-bending pipe by letting a current flow to a positive electrode and a negative electrode in an electrolyte, the method comprising:
 placing a mesh net having a shape corresponding to an inner shape of the multi-bending pipe and formed of an insulating material and an internal electrode disposed within the mesh net within the multi-bending pipe;   placing an external electrode outside the multi-bending pipe; and   applying a negative electrode to the internal electrode and the external electrode and applying a positive electrode to the multi-bending pipe such that the inner surface and the outer surface of the multi-bending pipe is electro-polished.   
     
     
         2 . The method of  claim 1 , wherein the mesh net is formed of a circular mesh net made of an insulating material. 
     
     
         3 . The method of  claim 1 , wherein the external electrode has a shape corresponding to an outer shape of the multi-bending pipe and is disposed along the outer surface of the multi-bending pipe in parallel to the outer surface of the multi-bending pipe. 
     
     
         4 . The method of  claim 1 , wherein the electrolyte is obtained by mixing sulfuric acid, phosphoric acid, distilled water, and a platinum additive. 
     
     
         5 . The method of  claim 1 , wherein the mesh net is formed of a flexible meshed electrode that is inserted into a bent portion section of the multi-bending pipe. 
     
     
         6 . The method of  claim 2 , wherein the mesh net is formed of a flexible meshed electrode that is inserted into a bent portion of the multi-bending pipe. 
     
     
         7 . The method of  claim 1 , wherein the multi-bending pipe is directly placed into an electrolyte container filled with the electrolyte in which the internal electrode and the mesh net are disposed inside and the external electrode is disposed outside the multi-bending pipe. 
     
     
         8 . The method of  claim 5 , wherein the flexible meshed electrode is a copper wire.